[Bug middle-end/96200] Implement __builtin_thread_pointer() and __builtin_set_thread_pointer() if TLS is supported

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96200

--- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> ---
On Linux/i386 and Linux/x86-64, thread pointer access is done via syscall.
On Linux/x86-64, __builtin_thread_pointer and __builtin_set_thread_pointer
may be implemented with FSGSBASE ISA.  Is it possible to implement these
builtins on Linux/i386 and Linux/x86-64 for all processors?